In the related art, in a lamp that allows the light emitted from a semiconductor light-emitting element to be incident on a light guide, the semiconductor light-emitting element is unitized into a light guide and assembled as a single optical component in a lamp housing such that the relative positions of the semiconductor light-emitting element and the light guide do not change. For example, in the vehicular lamp of Japanese Laid-Open Patent Publication No. 2013-191406, an LED is fixed at a position facing an light-incident portion (end face) of a light guide by a support member and both ends of the light guide are supported on a lamp housing by a separate support member so that the light guide is able to generate uniform light over the entire length.